全文获取类型
收费全文 | 1290篇 |
免费 | 69篇 |
国内免费 | 14篇 |
专业分类
化学 | 812篇 |
晶体学 | 27篇 |
力学 | 48篇 |
数学 | 219篇 |
物理学 | 267篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 25篇 |
2021年 | 43篇 |
2020年 | 38篇 |
2019年 | 34篇 |
2018年 | 32篇 |
2017年 | 57篇 |
2016年 | 56篇 |
2015年 | 58篇 |
2014年 | 55篇 |
2013年 | 126篇 |
2012年 | 110篇 |
2011年 | 124篇 |
2010年 | 83篇 |
2009年 | 71篇 |
2008年 | 86篇 |
2007年 | 78篇 |
2006年 | 42篇 |
2005年 | 45篇 |
2004年 | 50篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1972年 | 2篇 |
1907年 | 1篇 |
排序方式: 共有1373条查询结果,搜索用时 15 毫秒
41.
42.
Journal of Inclusion Phenomena and Macrocyclic Chemistry - Newly phthalocyanine derivative which carries 2,6-dimethoxyphenoxy bioactive groups as tetrakis from non-peripheral positions of the... 相似文献
43.
膜的动电特性研究中,往往采用流动电位方法。该方法中,Ag-Ag Cl测试电极的质量是影响测试准确性的关键要素。本文采用正交试验设计和方差分析,着重考察电解法制备Ag-Ag Cl电极过程中,电流强度(I)、氯化时间(t)、电解质溶液浓度(CHCl)、电极来源(n)、烘烤温度(T)、活化电极溶液浓度(CKCl)等因素对Ag-Ag Cl电极稳定性的影响。得到Ag-Ag Cl电极的最优制备参数为:电流密度3.0m A/cm2,氯化时间50min,盐酸浓度0.1mol·L-1,烘烤温度120℃,活化电极溶液(KCl)浓度0.001mol·L-1;最显著影响因素为电极来源,显著影响因素为氯化时间和烘烤温度。对最优条件组合下制备的AgAg Cl电极,进行了稳定性实验,结果表明:制备的电极具有较好的稳定性,24h内电极电位漂移量小于0.10mv,7天内电极电位漂移量小于0.2mv;在聚偏氟乙烯中空纤维超滤膜流动电位测试中,流动电位与流动压差具有良好的线性和可重复性,回归曲线R20.99,变化规律符合Helmholtz-Smoluehowski公式,可以较好满足膜的流动电位测试要求。 相似文献
44.
45.
Ersan Ronak Haj Alagoz Mehmet Abdullah Ertan-Bolelli Tugba Duran Nizami Burmaoglu Serdar Algul Oztekin 《Molecular diversity》2021,25(4):2247-2259
Molecular Diversity - In the present work, a series of bisbenzazole derivatives were designed and synthesized as antiproliferative agents. The antiproliferative activity of these compounds was... 相似文献
46.
We obtained the azo‐imine ligand (2,2′‐[4‐(5‐methoxy salicylidene‐4‐iminophenylazo)phenylimino]diethanol) (HL) and its Cu (II) complex (CuL) from the ethanol solution. The complex Cu(L)2 was obtained as single crystals from the CH3OH solution and structurally characterized. The electronic and photoluminescence properties of the ligand and its Cu (II) complex were investigated both in DMF solution and solid state. The oxidation and reduction behaviours of the compounds were studied in the solution and found that the redox processes are irreversible. Thermal studies show that the ligand has higher thermal stability than the CuL complex. Single crystals of the complex were obtained from slow evaporation of a DMF solution of the complex. Crystals of the complex showed a diffraction pattern; however, the structure of the complex was able to be solved. 相似文献
47.
Positivity - In this paper we investigate the distance of convergence in measure whenever the measure is not $$\sigma $$ -finite and identify the topological coreflection of this approach structure... 相似文献
48.
49.
A novel amperometric hydrogen peroxide biosensor based on pyrrole-PAMAM dendrimer modified gold electrode 总被引:1,自引:0,他引:1
Horseradish peroxidase (HRP) was immobilized into an electrochemically prepared copolymer of pyrrole–PAMAM (PAMAM; polyamidoamine) dendrimers for the construction of amperometric hydrogen peroxide biosensor. First, second, and third generation amidoamine–pyrrole dendrons having branched amine periphery and focal pyrrole functionality were synthesized via divergent pathway. Pyrrole dendrimers were covalently attached onto the electrode surface and polymerized by electrochemical copolymerization with pyrrole monomer. The synthesized dendrimers and copolymers have been characterized by FTIR-ATR and NMR. These copolymers have been utilized as conducting films for amperometric hydrogen peroxide sensing. The HRP retains its bioactivity after immobilization into the dendronized pyrrole-copolymers. Amperometric response was measured as a function of concentration of hydrogen peroxide, at fixed potential of +0.35 V vs. Ag/AgCl in a phosphate buffered saline (pH 7.5). The effect of pH and temperature of the medium, storage, and reusability properties were investigated. The results indicate an efficient immobilization of enzyme onto the PAMAM type dendrimer modified surface containing pyrrole monomer, which leads to high enzyme loading, and increased lifetime stability of the electrode. 相似文献
50.